Liquid droplet interproximal (interdental) cleaning apparatus/appliances use a CO2 or other gas stream to accelerate a volume of liquid and to produce liquid droplets therefrom, which are directed to the dental regions for cleaning. A CO2 gas stream is typically produced by the rapid expansion of a small amount of gaseous CO2 released from a CO2 reservoir, such as a cartridge.
The CO2 reservoir will typically include both liquid CO2 and gaseous CO2. Typically, only gaseous CO2 proceeds from the reservoir when the apparatus is in an upright orientation. The gaseous CO2 is directed into and then exits from a metered valve to form a gas stream.
A portion of the gas stream may be used to accelerate liquid from the reservoir into the gas stream to produce liquid droplets. However, when the apparatus is tilted, including below horizontal or even completely upside down, liquid CO2 enters the metered valve instead of gaseous CO2, which results in a significant increase in the amount of gas from the metered valve as the gas decompresses prior to and at the exit of the valve. This can result in the speed of the modified gas stream being excessive and/or the fluid being accelerated at a too high a rate, resulting ultimately in damage to the gingival or interproximal pockets of the dental region.
Hence, it is desirable to have a structural arrangement which protects against increases in the decompressing (expanding) gas from the gas reservoir, regardless of the orientation of the apparatus.